1. Field of the Invention
The field of this invention generally relates to packaging for drugs, and more particularly to a child resistant package for drugs.
2. Background of the Invention
The incorporation of child resistant features on drug packaging is well recognized as a significant factor in the reduction of childhood poisoning caused by ingestion of hazardous materials. In fact, the child resistance of packaging was such a significant factor that the U.S. Poison Prevention Packaging Act was enacted requiring packaging of certain materials to meet minimum standards of child resistance. Many packaging designs have been developed in order to meet the standards outlined in the Act.
One child resistant package design is found, for example, in U.S. Pat. No. 4,988,004. The design includes a blister sheet defining drug carrying blisters, a foil sheet that covers the blister sheet and encloses the blisters, and a reinforcing layer coupled to the foil sheet opposite to the blister sheet. The reinforcing layer includes perforated pull tabs that extend over the blister. An end of each pull tab lies flat against but is not coupled to the foil sheet. When used as designed, the package is bent, which causes the unsealed end of a pull tab to lift so that the user can grasp it and pull it off from over the foil covering the blister. After the tab is removed, a portion of the foil that covers the blister becomes exposed and the user pushes the contents of the blister through the foil. A disadvantage of such a design is that there is only one layer that provides any substantial child resistance. If the package is damaged or if a child is able to surpass that feature, the drug enclosed therein becomes easily accessible. A further disadvantage of the design is that the perforations that define the peel tabs extend to the outer edge of the package making it easier for the pull tabs to be removed by manipulating the outer edge of the package.
Another package design is found in U.S. Pat. No. 5,325,968. That design includes a blister sheet that includes drug carrying depressions and access depressions. A peelable sheet covers the depressions and encloses dosages within the drug carrying depression. A user is required to remove a portion of the peelable sheet that covers an access depression in order to grip a second portion of the peelable sheet that covers the drug carrying depression. The peelable sheet may be peeled from the drug carrying depression to gain access to the packaged drug. A shortcoming of the design is that, after the second portion of the peelable sheet covering one of the drug carrying depressions is removed, access to another drug carrying depression is made easier. In addition, there is only one sheet of material covering the drug carrying depression so if the package is damaged the drug may become exposed.
In another design, shown in U.S. Pat. No. 5,785,180, a child resistant package includes a blister sheet defining drug carrying blisters, a rupturable layer that seals the blisters and a nonrupturable layer that covers the rupturable layer. For each blister, a perforated pull tab is included on the nonrupturable layer that is designed to be difficult to remove. A user is required to pull the pull tab in a first direction and subsequently pull the same pull tab in a second direction perpendicular to the first direction. If the user is able to pull the tab as designed, the portion of the rupturable layer enclosing the associated blister becomes exposed so that the user can gain access to the contents of the blister by causing the rupture of the rupturable layer. One disadvantage of the package is that if the user does not pull the tab as designed, the tab will tear before being completely removed and a portion of the tab will remain over the blister, hindering access to the contents. A further disadvantage is that there is only one pull tab that forms a significant line of defense prior to gaining access to a potentially harmful substance.
Another package includes a blister layer defining drug carrying blisters, that is covered by a rupturable layer, an intermediate layer and a top layer, as shown in U.S. Pat. No. 5,339,960. The intermediate layer includes bendable breakaway panels defined by score lines that cover the rupturable layer. The top layer covers the intermediate layer and includes access panels that intersect the edge of the package. After removal of an access panel of the top layer, the user presses the associated blister and the contents is forced through the rupturable layer and past the bendable breakaway panel. Although the design includes dual layers covering the rupturable layer, only one easily removable access panel must be removed prior to gaining easy access to the contents of the associated blister.